Liquid crystal display device

ABSTRACT

Disclosed herein is an LCD device having a drive area directly formed inside a non-pixel area of a substrate without an additional drive IC. The LCD device includes a first substrate having a pixel area and a non-pixel area disposed peripherally to the pixel area. The pixel area has a thin film transistor and a pixel electrode in each sub-pixel defined by gate and data lines crossing each other. A second substrate formed in opposition to the first substrate includes a color filter layer and a black matrix layer. A liquid crystal layer is formed between the first and second substrates. An opening in the black matrix layer reveals an alignment mark, which is disposed on at least one of the first substrate and the second substrate.

This application claims the benefit of the Korean Patent Application No.P2005-46991, filed on Jun. 2, 2005, which is hereby incorporated byreference as if fully set forth herein.

TECHNICAL FIELD

The present disclosure relates to a liquid crystal display (LCD) device,and more particularly, to an LCD device which has a drive area formed ona non-pixel area of a substrate without an additional drive IC.

BACKGROUND

Among flat display devices, liquid crystal display (LCD) devices arewidely used for notebook computers, monitors, aircraft, and otherapplications. LCDs have the advantages of high contrast ratio, good grayscale level, low power consumption, and good motion quality.

In particular, LCD technology may be applied to ultra-thin displays,such as wall-mountable televisions, because the LCD device has a thinprofile. In addition, the LCD device is light in weight and has lowpower consumption; thus it may be used as a display device for anotebook computer which is driven by a battery. Also, the LCD device canbe fabricated in a small size and used for a display of a mobile phone.

Generally, the LCD device includes an upper substrate of a color filterarray substrate, a lower substrate of a thin film transistor arraysubstrate, and a liquid crystal layer of a dielectric anisotropy. Inthis case, the lower and upper substrates are positioned in oppositionto each other, and the liquid crystal layer is formed between the lowerand upper substrates. A plurality of pixels are formed, each of whichhas a thin film transistor TFT. A voltage is applied to thecorresponding pixel through a pixel-selection address line by switchingthe thin film transistor of the pixel region.

A light source (backlight) is provided to a rear surface of the LCDdevice. That is, the LCD device is formed in a transmitting mode,wherein the light emitted from the backlight is used to display imageson a screen. In this case, a color filter layer of red (R), green (G)and blue (B) colors is provided to the LCD device.

The LCD device may also be used for a desktop monitor as well as for anotebook computer, in which case the color filter layer of the LCDdevice preferably has high luminosity and chromaticity.

Hereinafter, an LCD device according to the related art will bedescribed with reference to the accompanying drawings.

FIG. 1 is a plan view of a general LCD device. FIG. 2 is a plan view ofan LCD device according to the related art.

As shown in FIG. 1, a general LCD device includes a TFT array substrate50 which is divided into a pixel area 52 for displaying images inside adotted line of FIG. 1, and a non-pixel area 54 outside the dotted lineof FIG. 1.

In the pixel area 52, there are a plurality of gate and data lines 61and 62 crossing each other to define sub-pixels. Also, a thin filmtransistor TFT (not shown) is formed adjacent to a crossing of the gateand data lines 61 and 62. Each sub-pixel has a pixel electrode (notshown) which is electrically connected with a drain electrode of thethin film transistor. The images are displayed by switching thecorresponding thin film transistor.

The non-pixel area 54 is provided with gate and data link lines 63 and64 respectively extended from the gate and data lines 61 and 62. Eachone end of the gate link lines 63 is connected with a gate drive IC 70,and each one end of the data link lines 64 is connected with a datadrive IC 80.

The gate and data drive IC 70 and 80 are mounted by a tape automatedbonding (TAB) method for connection with a printed circuit board (PCB)90. On the PCB 90, there are a plurality of elements such as integratedcircuits to generate various control signals and data signals foroperation of the LCD device.

Although not shown, the color filter array substrate of the LCD deviceincludes a color filter layer of red (R), green (G) and blue (B) colorfilter patterns, a black matrix layer for division of R, G and B colorfilter patterns and for light-shielding function, and a common electrodeto apply a voltage to the liquid crystal cells.

After cutting the LCD device to a desired size, processes for edgegrinding and polarizer attachment are performed. For the edge grindingprocess, the position of the LCD device is sensed by a charged-coupledevice (CCD) camera, and then a grinder grinds the edge of the LCDdevice. For the polarizer attachment process, after sensing the positionof the LCD device with the CCD camera, a polarizer is attached to theLCD device.

To sense the precise position of the LCD device, the CCD camera maybenefit from having an alignment mark. The alignment mark is formedcorresponding to the region where the data and gate drive ICs is formedprior to the processes of edge grinding and polarizer attachment. Forreference, the data and gate drive IC are connected with the LCD deviceafter the processes of edge grinding and polarizer attachment.

Recently, a new model has been proposed, wherein the gate drive area isformed on the TFT array substrate and the space for mounting the gatedrive IC is eliminated from the LCD device, thereby increasing the pixelarea of the LCD device. In this case, the alignment mark may be hiddenby the black matrix layer of the color filter array substrate.

In detail, as shown in FIG. 2, a PCB 190 is provided only correspondingto a data line part, and the PCB 190 is connected with a data drive IC180. In this state, a gate drive area 170 is formed inside a non-pixelarea 154 of the LCD device without the gate drive IC, thereby decreasingthe non-pixel area in size corresponding to the region where the gatedrive IC would be attached. Thus, an alignment mark corresponding to arelated art gate drive IC is formed in the gate drive area 170.

In case of the LCD device having no gate drive IC, the space formounting the gate drive IC is eliminated. That is, the alignment mark ishidden in the processes for edge grinding and polarizer attachment. Inother words, the gate drive area 170 is overlapped with a color filterarray substrate having a black matrix layer, and thus the alignment markis hidden by the black matrix layer.

In the general LCD device, the alignment mark is formed in the portionsincluding the gate and data drive ICs and having no black matrix layerso that it can be seen in the edge grinding and polarizer attachmentprocesses, and therefore, such processes are performed without anyproblem. However, in case of the LCD device having no gate drive IC, thealignment mark formed in the TFT array substrate is hidden by the colorfilter array substrate, so that the CCD camera cannot sense thealignment mark. That is, the alignment mark is hidden by the blackmatrix layer formed at the edge of the color filter array substrate.

SUMMARY

Accordingly, the present disclosure is directed to an LCD device whichhas a drive area formed on a non-pixel area of a substrate without anadditional drive IC.

According to one embodiment, the LCD device comprises a first substrateincluding a pixel area and a non-pixel area disposed peripherally to thepixel area. The pixel area has a thin film transistor and a pixelelectrode in each sub-pixel defined by gate and data lines crossing eachother. A second substrate is disposed in opposition to the firstsubstrate and includes a color filter layer and a black matrix layer. Aliquid crystal layer is disposed between the first and secondsubstrates. An alignment mark is disposed on at least one of the firstsubstrate and the second substrate. An opening in the black matrix layerreveals the alignment mark.

According to another embodiment, the LCD device includes a firstsubstrate having a pixel area and a non-pixel area disposed peripherallyto the pixel area. The pixel area has a thin film transistor and a pixelelectrode in each sub-pixel defined by gate and data lines crossing eachother. A second substrate is disposed in opposition to the firstsubstrate and includes a color filter layer and a black matrix layer. Aliquid crystal layer is disposed between the first and secondsubstrates. An alignment mark is disposed on the first substrate and isvisible through an opening in the black matrix layer.

According to another embodiment, the LCD device includes a firstsubstrate having a pixel area and a non-pixel area disposed peripherallyto the pixel area. The pixel area has a thin film transistor and a pixelelectrode in each sub-pixel defined by gate and data lines crossing eachother. A second substrate is disposed in opposition to the firstsubstrate and includes a color filter layer and a black matrix layer. Aliquid crystal layer is disposed between the first and secondsubstrates. An alignment mark is disposed on one of the first substrateand the second substrate and is defined by an opening in the blackmatrix layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a general LCD device;

FIG. 2 is a plan view of an LCD device according to the related art;

FIG. 3 is a plan view of an LCD device according to the presentdisclosure;

FIGS. 4A and 4B are plan and cross section views of an alignment markaccording to a first embodiment;

FIGS. 5A and 5B are plan and cross section views of an alignment markaccording to a second embodiment;

FIGS. 6A and 6B are plan and cross section views of an alignment markaccording to a third embodiment;

FIGS. 7A and 7B are plan and cross section views of an alignment markaccording to the fourth embodiment embodiment; and

FIGS. 8A and 8B are plan and cross section views of an alignment markaccording to the fifth embodiment embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to various preferred embodiments,examples of which are illustrated in the accompanying drawings. Whereverpossible, the same reference numbers will be used throughout thedrawings to refer to the same or like parts.

FIG. 3 is a plan view of an LCD device according to the presentdisclosure. FIGS. 4A and 4B are plan views of an alignment markaccording to a first embodiment. FIGS. 5A and 5B are plan views of analignment mark according to a second embodiment. FIGS. 6A and 6B areplan and cross section views of an alignment mark according to a thirdembodiment. FIGS. 7A and 7B are plan and cross section views of analignment mark according to a fourth embodiment. FIGS. 8A and 8B areplan and cross section views of an alignment mark according to a fifthembodiment.

As shown in FIG. 3, an LCD device according to the present disclosureincludes a TFT array substrate 254, a color filter array substrate 252,a liquid crystal layer (not shown), and an alignment mark 250.

The TFT array substrate 254 includes a pixel area for displaying imagesand a non-pixel area for supplying various signals to the pixel area.The pixel area is provided with switching elements to change analignment direction of the liquid crystals. The color filter arraysubstrate 252 is comprised of a color filter layer for representingcolors, and a black matrix layer 260 for preventing light leakage. Also,the liquid crystal layer (not shown) is formed between the color filterarray substrate and the TFT array substrate. Then, a portion of theblack matrix layer 260 may be removed to form an opening therein thatreveals the alignment mark 250, which may aid in determining the preciseposition of the LCD device in the steps of edge grinding and polarizerattachment. As used herein, the term “reveals” means makes visible ordefines.

Although not shown, the pixel area of the TFT array substrate 254 isprovided with a plurality of gate and data lines crossing each other todefine sub-pixels, with a gate insulating layer disposed between thegate and data lines. A plurality of thin film transistors TFTs areformed adjacent to the crossings of the gate and data lines, and a pixelelectrode is electrically connected with each thin film transistor TFTand formed in an opening of each sub-pixel.

The non-pixel area is provided with a gate drive area 270 directlyformed on the TFT array substrate 250, and a data drive IC 280 connectedwith the data line by a data link line extended from the data line. Thedata drive IC 280 is connected with a PCB 290. That is, the PCB 290 isformed corresponding to a data line part, and the PCB 290 is connectedwith the data drive IC 280. However, the gate drive area 270 may bedirectly formed in the non-pixel area of the LCD device without formingan additional gate drive IC.

The gate and data lines may be formed of a light-shielding material, forexample, copper (Cu), aluminum (Al), aluminum neodymium (AlNd),molybdenum (Mo), chrome (Cr), titanium (Ti), tantalum (Ta), ormolybdenum-tungsten (MoW).

Also, the alignment mark 250 may be formed when forming the gate or dataline, together. As shown in FIGS. 4A, 4B, 5A and 5B, a portion of theblack matrix layer 260 overlapped with the alignment mark 250 may beremoved, thereby forming an opening in the black matrix layer 260 andpreventing the alignment mark 250 from being hidden by the black matrixlayer 260. The opening in the black matrix layer 260 thus reveals thealignment mark 250 when viewed from a plan view perspective, as shown inthe figures. As used herein, the term “reveals” means makes visible ordefines. As shown in FIGS. 4A and 4B, the alignment mark 250 may beformed on the TFT array substrate 254 by patterning the light-shieldingmaterial layer. The alignment mark 250 shown in FIGS. 4A and 4B has arelief structure. Also, as shown in FIGS. 5A and 5B, the alignment mark250 may be formed on the TFT array substrate 254 having an intagliostructure by removing a portion of the light-shielding metal layer 500.The two substrates 252 and 254 may be aligned to show the alignment markthrough the opening in the black matrix layer 260. For reference, thereference numeral 600 corresponds to a portion having no pattern betweenthe black matrix layer 260 and the alignment mark 250.

The color filter array substrate 252 includes a color filter layer, ablack matrix layer 260, and a common electrode. The color filter layeris disposed in opposition to the pixel area so as to represent colors,the black matrix layer 260 is disposed in opposition to the periphery ofthe sub-pixels and the non-pixel area so as to prevent light leakage,and a common electrode is disposed in opposition to the pixel electrodeso as to apply an electric field to the liquid crystal layer.

The black matrix layer 260 is formed by depositing or coating a materialhaving an optical density of 3.5 or above, for example, an inorganicmaterial of chrome oxide (CrOx) or a metallic material of chrome (Cr).The alignment mark 250 may be formed when forming the black matrixlayer, together. As shown in FIGS. 6A, 6B, 7A and 7B, one or moreportions of the black matrix layer 260 may be removed to form an openingtherein that reveals the alignment mark from a plan view perspective. Asused herein, the term “reveals” means makes visible or defines.

As shown in FIGS. 6A and 6B, the alignment mark 250 may be formed tohave a relief structure on the color filter array substrate 252 bypatterning the black matrix layer 260. Also, as shown in FIGS. 7A and7B, the alignment mark 250 may be formed on the color filter arraysubstrate 252 having an intaglio structure by patterning the blackmatrix layer 260. The two substrates 252 and 254 may be aligned to showthe alignment mark 250 revealed by the opening in the black matrix layer260. For reference, the reference numeral 600 corresponds to a portionhaving no pattern between the black matrix layer 260 and the alignmentmark 250.

As shown in FIGS. 8A and 8B, the alignment mark may include a firstalignment mark 250 a formed on a TFT array substrate, and a secondalignment mark 250 b formed on a color filter array substrate. Forexample, the second alignment mark 250 b having a relief structure maybe positioned inside the first alignment mark 250 a having an intagliostructure. Alternatively, the second alignment mark 250 b having arelief structure may be positioned inside the first alignment mark 250 ahaving a relief structure. The first alignment mark 250 a may be formedat the same time as the light-shielding metal layer 500 for the gate ordata line, and the second alignment mark 250 b may be formed at the sametime as the black matrix layer. The two substrates 252 and 254 may bealigned to show the second alignment mark 250 b within the firstalignment mark 250 a. For reference, the reference numeral 600corresponds to portions having no pattern, for example, between thelight-shielding material layer 500 and the second alignment mark 250 b,and between the light shielding material layer 500 and the black matrixlayer 260.

Alternatively, the first alignment mark having a relief or an intagliostructure may be positioned inside the second alignment mark having anintaglio or a relief structure.

In this case, the first and second alignment marks may be used whenbonding the TFT array substrate and the color filter array substrate toeach other in addition to the edge grinding and polarizer attachmentprocesses.

The alignment mark may be formed at the same time as the gate or dataline of the TFT array substrate. Alternatively, the alignment mark maybe formed at the same time as the black matrix layer of the color filterarray substrate.

Also, the alignment mark may be comprised of the first alignment mark onthe TFT array substrate formed at the same time as the gate or dataline, and the second alignment mark on the color filter array substrateformed at the same time as the black matrix layer. Also, the alignmentmark may be comprised of the first alignment mark on the TFT arraysubstrate formed at the same time as the black matrix layer, and thesecond alignment mark on the color filter array substrate formed at thesame time as the black matrix layer.

In the LCD device having the drive area directly formed on thesubstrate, the black matrix layer may be partially removed to form anopening that reveals the alignment mark, which may aid in determiningthe correct and precise position of the LCD device in the steps of edgegrinding and polarizer attachment.

In the above drawings, the alignment mark is formed in the shape of across. However, it is not limited to the cross shape.

A data drive area as well as the gate drive area may be directly formedinside the non-pixel area of the TFT array substrate, thereby removingthe data drive IC. In this case, a portion of the black matrix layercovering the data drive area may be removed, forming an opening in theblack matrix layer over the drive area and preventing the alignment markfrom being hidden by the black matrix layer. Accordingly, it may bepossible to sense the correct and precise position of the LCD device inthe steps of substrate bonding, edge grinding, and polarizer attachment.

In the LCD device having the drive area directly formed inside thenon-pixel area of the substrate, a portion of the black matrix layercovering the drive area of the non-pixel area may be removed to form anopening in the black matrix layer that reveals the alignment mark.Accordingly, it may be possible to sense the correct and preciseposition of the LCD device in the steps of edge grinding and polarizerattachment.

Also, the alignment mark may be formed at the same time as the gate ordata line of the TFT array substrate, or as the black matrix layer ofthe color filter array substrate. Thus, the alignment mark may be formedwithout an additional step.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present disclosurewithout departing from the spirit or scope of the invention. Thus, it isintended that the present disclosure covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. An LCD device comprising: a first substrate comprising a pixel areaand a non-pixel area disposed peripherally to the pixel area, the pixelarea having a thin film transistor and a pixel electrode in eachsub-pixel defined by gate and data lines crossing each other; a secondsubstrate having a color filter layer and a black matrix layer, thesecond substrate disposed in opposition to the first substrate; a liquidcrystal layer disposed between the first and second substrates; and analignment mark disposed on at least one of the first substrate and thesecond substrate, wherein an opening in the black matrix layer revealsthe alignment mark.
 2. The LCD device of claim 1, wherein the alignmentmark comprises a first substrate portion disposed on the firstsubstrate.
 3. The LCD device of claim 2, wherein the first substrateportion is formed at the same time as the gate line.
 4. The LCD deviceof claim 2, wherein the first substrate portion is formed at the sametime as the data line.
 5. The LCD device of claim 2, wherein the firstsubstrate portion is formed at the same time as the black matrix layer.6. The LCD device of claim 1, wherein the alignment mark comprises asecond substrate portion disposed on the second substrate.
 7. The LCDdevice of claim 6, wherein the second substrate portion is formed at thesame time as the black matrix layer.
 8. The LCD device of claim 1,wherein the alignment mark comprises one of an intaglio structure and arelief structure.
 9. The LCD device of claim 1, wherein the alignmentmark comprises a first substrate portion disposed on the first substrateand a second substrate portion disposed on the second substrate.
 10. TheLCD device of claim 9, wherein the first substrate portion is formed atthe same time as the gate line.
 11. The LCD device of claim 9, whereinthe first substrate portion is formed at the same time as the data line.12. The LCD device of claim 9, wherein the first substrate portion isformed at the same time as the black matrix.
 13. The LCD device of claim9, wherein the second substrate portion is formed at the same time asthe black matrix layer.
 14. The LCD device of claim 9, wherein the firstsubstrate portion comprises one of a first intaglio structure and afirst relief structure and the second substrate portion comprises one ofa second relief structure and a second intaglio structure.
 15. The LCDdevice of claim 9, wherein the second substrate portion is positionedinside the first substrate portion.
 16. The LCD device of claim 9,wherein the first substrate portion is positioned inside the secondsubstrate portion.
 17. The LCD device of claim 1, wherein the non-pixelarea has a drive area formed thereon.
 18. The LCD device of claim 17,wherein the drive area corresponds to a gate drive area connected withthe gate line.
 19. The LCD device of claim 17, wherein the drive areacorresponds to a data drive area connected with the data line.
 20. TheLCD device of claim 1, wherein the black matrix layer is disposed overthe non-pixel area except a portion including the alignment mark.
 21. AnLCD device comprising: a first substrate comprising a pixel area and anon-pixel area disposed peripherally to the pixel area, the pixel areahaving a thin film transistor and a pixel electrode in each sub-pixeldefined by gate and data lines crossing each other; a second substratehaving a color filter layer and a black matrix layer, the secondsubstrate disposed in opposition to the first substrate; a liquidcrystal layer disposed between the first and second substrates; and analignment mark disposed on the first substrate and visible through anopening in the black matrix layer.
 22. An LCD device comprising: a firstsubstrate comprising a pixel area and a non-pixel area disposedperipherally to the pixel area, the pixel area having a thin filmtransistor and a pixel electrode in each sub-pixel defined by gate anddata lines crossing each other; a second substrate having a color filterlayer and a black matrix layer, the second substrate disposed inopposition to the first substrate; a liquid crystal layer disposedbetween the first and second substrates; and an alignment mark disposedon one of the first substrate and the second substrate and defined by anopening in the black matrix layer.